I removed the thick black heatshrink cover on a 30 amp BP Hobbies ESC as shown.
Cut out the bottom of the U 2 to put the large flat heatsink flush with the incoming airflow to the fan. The ESC plate was room temperature after a 1 minute run a WOT from a 2200 mahr Nano Tech 3 cell. The ESC clears the black bottom plastic with plenty of room. There is no heating of either side of the ESC.

I had a stock plane of 1 pound 16 oz. RTF. With the modifications it now is 1 pound 11.1 oz.
Stock the thrust was 15 oz.